Vapor electric device



May 23, 1944. H. c. MEYERS 2,349,633

VAPOR ELECTRI C DEVICES Filed Jan. 23, 1943 wnuzsss; INVENTOR Henr 62 M era. flffiad v .9

'ATTORNEY Patented May 23, 1944 VAPOR ELECTRIC DEVICE Henry C. Myers, Geneva, Ill., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application January 23, 1943, Serial No. 473,309

8 Claims.

My invention relates to a vapor electric device, and particularly to a control means for dividing load current between a plurality of groups of vapor electric valves.

In the operation of vapor electric converters, it is customary to provide a plurality of groups of parallel valves in order to improve the load factor characteristics of all of the valves. Difllculty has heretofore been experienced in securing uniform division of load between the various valve groups because of unbalance in the supply potentials caused by other loads on the supply system. This trouble has been particularly noticeable with the double biphase devices, or socalled four-phase connections, where a voltage unbalance of 3% on the primary side of the rectifier transformer may frequently result in a load unbalance of as much as 50% on the secondary side of the transformer. In other words, one group of two valves will carry 50% greater current than the other group of two valves.

In the control system according to my invention, I provide means for regulating the valve groups so that substantially uniform load division will be secured between the valve groups regardless of any unbalance that might be experienced because of unbalance on the primary ide of the transformer. I secure thi result by providing substantially independent control systems for each of the valve groups, each control system having a phase-shifting network associated therewith, and by supplying a control factor to the phase-shifting network proportional to the difference in the load currents supplied by the various valve groups. tards the firing angle of the groupcarrying the larger current and advances the firing angle of the low current group until the groups are substantially evenly proportioned as to load characteristic.

It is, accordingly, an object of my invention to provide a control system for balancing the load in a plurality of valve groups.

A further object of my invention is to provide a phase-shifting system for equalizing the current output of a plurality of parallel operating valve groups.

'It'is a further object of my invention to provide an effective control factor proportional to the unbalanced current between the plurality of parallel operating valve groups.

Other objects and advantages of my invention will be apparent from the following detailed description taken in conjunction with the accompanying drawing, in which the single figure is a schematic illustration of an electric converter embodying my invention.

In the illustrated embodiment of my invention, according to the figure, a polyphase alternating current circuit 10 is connected to a direct-current Thi control potential recircuit II by means of a suitable rectifier transformer I2, herein illustrated as of the double biphase type having a Scott-connected primary winding l3 and a double biphase secondary winding l4 interconnected by means of an interphase transformer IS. The phase terminals of the bi phase groups A and B are connected to vapor electric valves herein illustrated as of the makealive type, each valve comprising a vaporizable reconstructing cathode ll of suitable material, such as mercury, a cooperating anode l8 and having a make-alive electrode 19 in contact with the cathode ll, all being contained in a suitable evacuated container 20.

Each valve group A and B is provided with an excitation system in the form of an impulsing network 2 |22, herein illustrated as of the wavedistorter impedance-network type, each of the wave distorter networks 2l-22 being connect-ed to substantially independent sources of control potential such as the phase windings 2324 of a control transformer 29, herein illustrated as of the Scott-connected transformer type.

Connected in-ser'ies between each of the sources 23-24 of control potential and the impulsing networks 2l22 are phase-shifting impedance networks 25-26 each having variable reactors 2l28 for shifting the phase of the potential supplied to the associated impulsing network.

To secure a control potential proportiona1 to the load on each of the valve groups A and B, I have provided current transformers 3l interlinked with the anode leads of each phase group A and B. Since the current in the anode leads is unidirectional in character, means must be provided to prevent saturation of the cores of transformers 303l. Where as shown there is an even number of anode leads per phase group, the leads may be reversely associated with the core as shown, but where there are an uneven number of leads, or for any reason a unilateral excitation i present, the cores may be constructed with an air gap or other well known means for preventing saturation.

' The output potential of each of the control transformers is rectified by a suitable means such as full-Wave rectifiers 32-33 and are balanced against each other in the saturable reactors 21-48. This is easily accomplished by providing a plurality of windings corresponding in number to the valve groups A-B on each of the variable reactors 2l28 and applying current from each of the control transformers 30-3! through a winding on, each of the variable reactors 21-28. The winding 35 on the variable reactor 21 associated with the phase group, such as A, from which the control potential is obtained is so wound as to retard the phase angle of the potential applied to the impulsing network 2 I, while the control winding 36 on the variable reactor 28 of the remaining phase groups is so Wound as to advance the phase angle of the potential applied to the i-mpulsing networks 22 of the remaining phase groups? m V In this manner it will be apparent that if the phase groups are carrying equal currents, the onects of all of the coils will balance out, so that no effect will be had on the variable reactor. However, if one of the groups is carrying excessive current or unbalance current between the groups, the eifect will be proportional to the embodiment of my invention, it Willbe apparent that the load balancing system may be applied to any multiple phase" groups, or even to two parallel operating converters, without'departing fromthe true spirit of my 'inyention or the scope of the appended claims.

I claim as my inventionf 1. A load balancing system for a conversion system having a plurality of parallel operating valve groups, a substantiallyindependent impulsing system for each of said'yalve groups, a phase shifting impedance network for each 'of said impulsing systems, a variable reactor in each of said networks, sources of direct current potential each proportional to the current carried by the respective said valve group, reversely wound windings on said .variable reactors and means for applying said potentials to said wind ings.

2. An electric conversion system having a phirality of parallel operating valve groups, a con: trol system for each valve group providing control impulse for the valves thereof, means for shifting the phase angle of the impulses of each control system, means for providing potentials proportional to the load on each valve system and means for impressing said potentials on said phase shifting means for substantially equalizing the load on each valve group.

3. An electric conversion system comprising transformer means providing a pair of phase groups, vapor-electric valves of the make-alive type connected to the phase terminals of said transformer means, impulsing means for supplying control impulses to the make-alive electrodes of each valve group, a phase shifting network for the impulsing means of each group, means for securing potentials respectively proportional to the load on each hase" group and means for impressing said potentials on the'phase shifting networks for equalizing the load on the phase groups.

4. An electric conversion system comprising transformer means p fpvi'ding' a pair of phase groups, vapor-ele'ctric valves 'of themake alive ype eonn'e teat th hase rx ipals of said s me m an impu s s. eant or 9- p lying control impulses to the make aliv elec t e r each valve oup. a Phea's i s work for the impulsing means of each group, means for securing potentials respectively prop iieee @131 load on each ha e ro P- posed winding means inieac h phase shifting net- "work and means for impressing said potentials on said winding means for shifting the phase of the control impulses to equalize the loads on the phase groups.

5. An electric current conversion system intercgnnecting two dissimilar electric circuits one of which is a polyphase alternating current circuit comprising transformer means for providing a plurality of phase groups, electric valves connected to the phase terminals of each phase group, a control electrode in each of said valves, .s qgttq s tem inc ud n a c ntro s c fi a as: page group a Phas shiftin frie er seda ith sah cont i witi ar a le r actor in each phase shifting network, means for secu in a Potent a vrpp rt qml to h loa 31 9W5 9-1 9 w ndin mean assented W th eac va ble r ct and conn c n imess the s i Pr o t na 6 t e oad 9 t W ndm me o vary n he hase Peti io i h c nt i uit ltoequa i the adin on th Phas r p fi- A ec i cu r nt sove ei ns-1 mm 9 111+ P g p a s u c o Supply. fio m eans f r e fidin t phase roups a lu l t o ra er .e e ri a e'm an for a h group, m an fe ba anc n cu e t e n the the r ups slud n an impuls n r uit ta ea h a 91, 91 a Pha e Shi n e a t for e c pulsing circuit, a variable reactor in each of ei Phase sh ti etwor s means assoc t s with h phas r u fe Pr idin a t g p orer i e 9 he u e t t mand mea 9 rr e he ma m 9 a ar a l act f i mount p e o t onal to he d en between said voltages.

' a la tr e w est con e sion system ompris n a purg o u l nsiormer means e i din We w s r s a l r lit of vapor e ect c valve means r ch ro mean bel egin eu ren h t een th rhe c' s in lu i m ulses ircu or e c Phase eas a pha e hi n ne o k r h i ulse c rcui a ia c o n e of a d phese'shiitin m e k m a s associated i ea h Phase rou r i in a l e mpQr iQe l 9 he cu en her i and eversa scemente Wi n m an o ch o s iable reactors energized from said voltages for varying the reactance of the variable reactors.

8. An electric current conversion system comr sing a s p l i i mdusin two -9 phase phase groups, two electric valves for each phase group, an auxiliary transformer associated with each phase group having a terminal voltage proportional to current carried by the phase group, an exciting system having a substantially independent excitation circuit for each phase group, a phase shifting network for each excitation circuit, means for rectifying the output of each or said transformers, a phase shifting re-, actor in each of said phase shifting networks, and means for inversely influencing" said phase shitting reactor in proportion to. the diiference between rectified output of said auxiliary trans: formers, i C- 

